Giant bubbles of gas that erupted from the core of the Milky Way galaxy millions of years ago are expanding out into space at mind-blowing speeds, according to new observations that may help reveal how the strange balloon-like lobes formed.

Scientists are finding more evidence of a galactic 'skeleton' lurking inside the appendages of the Milky Way, and studying these massive 'bones' could help researchers get a better idea of what our galaxy looks like from the outside.